ABSTRACT: Hypertension (HTN) and elevated blood pressure (EBP) lead to appreciable morbidity in pediatric patients, affecting them throughout life. Three to five percent of children have HTN, a rate that is steadily increasing. Almost 40% of pediatric HTN patients have left ventricular hypertrophy at diagnosis, suggesting delays in diagnosis and management initiation are affecting patients. Comprehensive, evidence-based guidelines for HTN diagnosis and management were updated in August 2017, but it is uncertain how to best implement HTN guidelines and reduce harm from failure to properly diagnose and manage HTN. Research by this investigative team with a national group of 30 primary care practices significantly reduced the recognition of elevated BP error rate, but strategies to move from recognition to diagnosis and management are unclear. Implementation research on primary and subspecialty care integration around HTN can serve as a model for other pediatric chronic conditions. Quality improvement collaboratives (QICs) often bring together either primary or subspecialty care physicians, but few integrate both primary and subspecialty care physicians to create comprehensive care improvement. It is unclear if pediatricians can effectively diagnose and manage chronic conditions like HTN with subspecialist back-up only, and it is uncertain how to effectively integrate primary and subspecialty care to reduce the harmful sequelae of pediatric HTN. This grant proposes to conduct a multisite, prospective, cluster-randomized trial, broadening and deepening our prior work on recognition of pediatric elevated BP, which will test methodologies to ensure every pediatric patient is screened, and if HTN or EBP are present, diagnosed and managed appropriately and expeditiously. This project will randomize at least 60 pediatric practices from across the country in a stepped-wedge fashion to a HTN QIC a) without subspecialist involvement, b) with subspecialist involvement and c) with pediatrician HTN diagnosis and management, and subspecialist back-up. It will also serve as a test case for whether pediatricians can diagnose and manage common chronic conditions (e.g., HTN) with a supporting subspecialist advisor. This proposal responds to AHRQ's Funding Opportunity Announcement PA-15-339, designed to develop evidence to improve safety in ambulatory care settings and focuses on children in rural and urban settings, AHRQ priority populations. This proposal, led by an experienced research team, will identify a clear implementation strategy for rigorous, evidenced-based pediatric HTN diagnosis and management, and highlight a model to increase primary and subspecialty care integration that can be reproduced across other chronic conditions.